Ubuntu Manpage: npm-dedupe - Reduce duplication in the package tree

NAME

npm-dedupe - Reduce duplication in the package tree

Synopsis
npm dedupe
npm ddp

aliases: ddp

Description
Searches the local package tree and attempts to simplify the overall structure by moving dependencies
further up the tree, where they can be more effectively shared by multiple dependent packages.

For example, consider this dependency graph:

a
+-- b <-- depends on c@1.0.x
| `-- c@1.0.3
`-- d <-- depends on c@~1.0.9
`-- c@1.0.10

In this case, npm dedupe will transform the tree to:

a
+-- b
+-- d
`-- c@1.0.10

Because of the hierarchical nature of node's module lookup, b and d will both get their dependency met by
the single c package at the root level of the tree.

In some cases, you may have a dependency graph like this:

a
+-- b <-- depends on c@1.0.x
+-- c@1.0.3
`-- d <-- depends on c@1.x
`-- c@1.9.9

During the installation process, the c@1.0.3 dependency for b was placed in the root of the tree. Though
d's dependency on c@1.x could have been satisfied by c@1.0.3, the newer c@1.9.0 dependency was used,
because npm favors updates by default, even when doing so causes duplication.

Running npm dedupe will cause npm to note the duplication and re-evaluate, deleting the nested c module,
because the one in the root is sufficient.

To prefer deduplication over novelty during the installation process, run npm install --prefer-dedupe or
npm config set prefer-dedupe true.

Arguments are ignored. Dedupe always acts on the entire tree.

Note that this operation transforms the dependency tree, but will never result in new modules being
installed.

Using npm find-dupes will run the command in --dry-run mode.

Note that by default npm dedupe will not update the semver values of direct dependencies in your project
package.json, if you want to also update values in package.json you can run: npm dedupe --save (or add
the save=true option to a npm help configuration file to make that the default behavior).

Configuration

global-style
• Default: false

• Type: Boolean

Causes npm to install the package into your local node_modules folder with the same layout it uses with
the global node_modules folder. Only your direct dependencies will show in node_modules and everything
they depend on will be flattened in their node_modules folders. This obviously will eliminate some
deduping. If used with legacy-bundling, legacy-bundling will be preferred.

legacy-bundling
• Default: false

• Type: Boolean

Causes npm to install the package such that versions of npm prior to 1.4, such as the one included with
node 0.8, can install the package. This eliminates all automatic deduping. If used with global-style this
option will be preferred.

strict-peer-deps
• Default: false

• Type: Boolean

If set to true, and --legacy-peer-deps is not set, then any conflicting peerDependencies will be treated
as an install failure, even if npm could reasonably guess the appropriate resolution based on non-peer
dependency relationships.

By default, conflicting peerDependencies deep in the dependency graph will be resolved using the nearest
non-peer dependency specification, even if doing so will result in some packages receiving a peer
dependency outside the range set in their package's peerDependencies object.

When such and override is performed, a warning is printed, explaining the conflict and the packages
involved. If --strict-peer-deps is set, then this warning is treated as a failure.

package-lock
• Default: true

• Type: Boolean

If set to false, then ignore package-lock.json files when installing. This will also prevent writing
package-lock.json if save is true.

When package package-locks are disabled, automatic pruning of extraneous modules will also be disabled.
To remove extraneous modules with package-locks disabled use npm prune.

omit
• Default: 'dev' if the NODE_ENV environment variable is set to 'production', otherwise empty.

• Type: "dev", "optional", or "peer" (can be set multiple times)

Dependency types to omit from the installation tree on disk.

Note that these dependencies are still resolved and added to the package-lock.json or npm-shrinkwrap.json
file. They are just not physically installed on disk.

If a package type appears in both the --include and --omit lists, then it will be included.

If the resulting omit list includes 'dev', then the NODE_ENV environment variable will be set to
'production' for all lifecycle scripts.

ignore-scripts
• Default: false

• Type: Boolean

If true, npm does not run scripts specified in package.json files.

Note that commands explicitly intended to run a particular script, such as npm start, npm stop, npm
restart, npm test, and npm run-script will still run their intended script if ignore-scripts is set, but
they will not run any pre- or post-scripts.

audit
• Default: true

• Type: Boolean

When "true" submit audit reports alongside the current npm command to the default registry and all
registries configured for scopes. See the documentation for npm help audit for details on what is
submitted.

bin-links
• Default: true

• Type: Boolean

Tells npm to create symlinks (or .cmd shims on Windows) for package executables.

Set to false to have it not do this. This can be used to work around the fact that some file systems
don't support symlinks, even on ostensibly Unix systems.

fund
• Default: true

• Type: Boolean

When "true" displays the message at the end of each npm install acknowledging the number of dependencies
looking for funding. See npm help npm fund for details.

dry-run
• Default: false

• Type: Boolean

Indicates that you don't want npm to make any changes and that it should only report what it would have
done. This can be passed into any of the commands that modify your local installation, eg, install,
update, dedupe, uninstall, as well as pack and publish.

Note: This is NOT honored by other network related commands, eg dist-tags, owner, etc.

workspace
• Default:

• Type: String (can be set multiple times)

Enable running a command in the context of the configured workspaces of the current project while
filtering by running only the workspaces defined by this configuration option.

Valid values for the workspace config are either:

• Workspace names

• Path to a workspace directory

• Path to a parent workspace directory (will result in selecting all workspaces within that folder)

When set for the npm init command, this may be set to the folder of a workspace which does not yet exist,
to create the folder and set it up as a brand new workspace within the project.

This value is not exported to the environment for child processes.

workspaces
• Default: null

• Type: null or Boolean

Set to true to run the command in the context of all configured workspaces.

Explicitly setting this to false will cause commands like install to ignore workspaces altogether. When
not set explicitly:

• Commands that operate on the node_modules tree (install, update, etc.) will link workspaces into the
node_modules folder. - Commands that do other things (test, exec, publish, etc.) will operate on the
root project, unless one or more workspaces are specified in the workspace config.

This value is not exported to the environment for child processes.

include-workspace-root
• Default: false

• Type: Boolean

Include the workspace root when workspaces are enabled for a command.

When false, specifying individual workspaces via the workspace config, or all workspaces via the
workspaces flag, will cause npm to operate only on the specified workspaces, and not on the root project.